Medical examinations to identify and diagnose hearing defects have historically involved physical examination of the ear canal and observing the subjective response to sound stimulus. Generally, the subjective sensitivity to volume has been routinely measured at several auditory frequencies. Most recently, the evoked action potentials resulting from auditory stimulation and auditory brainstem responses have been measured in an effort to identify more specifically the cause and degree of hearing loss and other hearing defects. Auditory brainstem response measurements involve auditory stimulation and measurement of the magnitude and response time of electrical signals originating from the otic nerve and brainstem in response to the auditory stimulus. The electrical signals are detected by using non-invasive electrodes mounted on the skin surface.